Abstract: Community members possess information relating to the community, and share that information with other community members to further the goals of the whole community. Some communities—such as geographic positioning system users, music lovers and mail-order businesses—indirectly hire a professional staff to gather information by purchasing professionally assembled directories. However, professionally assembled directories introduce costs for aggregating what community members may already know, and the professional staff's information may not be as accurate as information held by the members. However, simply assembling data from community members may introduce problems of data quality—some community members may be careful, some may be sloppy and some may be malicious.